FOXBOROUGH, Mass. -- LaDainian Tomlinson spent most of the game bundled up in a parka on the sideline on a freezing, windy day at Gillette Stadium.
The pain Philip Rivers felt from his sprained right knee was matched by the two interceptions he threw.
Combine the two, and that was not going to get the job done against the undefeated New England Patriots.
The aching San Diego Chargers lost, 21-12, as the Patriots improved to 18-0 and advanced to their fourth Super Bowl in seven seasons. All the Chargers points came on Nate Kaeding field goals.
To have a legitimate chance at a huge upset, however, Norv Turner's team needed to have all its star players healthy.
Of the three big-name starters who entered the game battling injuries for the Chargers, Tomlinson seemed to have the best chance to play, but he was only able to go on the first two series. He carried on the game's first two plays for a total of five yards, then caught a 1-yard swing pass from Rivers on the next drive before retreating to the sideline. Tomlinson rushed for only 75 yards in three playoff games.
"He really couldn't get started," Turner said. "He went and tried to go and just didn't have the power to push off."
The team announced the two-time NFL rushing champion had a sore knee and could return.
"From getting it reinjured the first play, I just knew I didn't have it," Tomlinson said. "I'm kind of at a loss for words."
Tomlinson, who hyperextended his left knee in the second quarter of a 28-24 upset win over the Indianapolis Colts a week earlier, was replaced by Michael Turner and Darren Sproles. Turner rushed for 65 yards on 17 carries, although had just 25 yards after halftime. Sproles finished with 34 yards rushing on three caries, along with two receptions for 5 yards.
"They have great depth at that position," Patriots coach Bill Belichick said. "Tomlinson's a great player, but they've got a lot of other ones, too."
Rivers started despite being listed as doubtful on the injury report, and Pro Bowl tight end Antonio Gates played for the second straight week with a dislocated left big toe.
Rivers completed 19-of-37 passes for 211 yards, with no touchdowns and two interceptions. Both of the interceptions occurred during a span of four plays late in the second quarter, and the Patriots turned one of the turnovers into a touchdown.
Rivers released the ball as he was going down deep in his own territory and was picked off by Asante Samuel, giving the Patriots the ball at the San Diego 24. Two plays later, Tom Brady hit Jabar Gaffney on a 12-yard touchdown pass.
"I felt that it was a pretty gutsy effort for him to come out there, play the whole game and play well," Patriots linebacker Mike Vrabel said.
Gates, who had 75 receptions for 984 yards and nine touchdowns during the regular season, was a non-factor with two receptions for 17 yards.
Copyright 2007 by The Associated Press